Major soda makers, including Coca-Cola, PepsiCo and Dr Pepper Snapple Group, will start displaying calorie counts on vending machines and encourage consumers to make lower-calorie choices, starting in 2013.

The beverage industry initiative, called the Calories Count Vending program, will launch first in municipal buildings in Chicago and San Antonio, where government employees are participating in a “wellness challenge” to see who can make greater improvements in their health (as measured by factors like weight loss and lower blood pressure). The winning city gets a $5 million grant from the American Beverage Association.

Soda companies said they planned to roll out the program nationwide in 2013 in an effort to curb the nation’s obesity epidemic. The initiative is the industry’s latest move to counter growing criticism of sugary beverages as a major cause of obesity in the U.S. and to fend off cities’ efforts to reduce consumption.

Last month, New York City passed an historic ban on the sale of sugary drinks larger than 16 oz., the first of its kind in the U.S. Cambridge, Mass., is considering doing something similar, while several other cities and communities are either raising soda taxes or voting to institute them.

The new vending machine labels will encourage consumers to “Check Then Choose” or “Try a Low-Calorie Beverage.” Calorie counts will also be inserted on buttons. The plan falls in line with the Affordable Care Act’s requirement that vending machines and restaurant chains with more than 20 locations display calorie information. Last month, McDonald’s also started printing calorie counts on its menus nationwide in advance of the new labeling requirements, which aren’t expected to take effect until the end of 2013.

So, will calorie information change Americans’ dietary habits? Maybe. Some early research has suggested that calorie counts didn’t do much to curb fast-food consumption. But later studies have found that calorie information, when presented clearly — and at the point of sale — does tend to sway people’s eating and drinking behaviors. In a December study published in the American Journal of Public Health, for example, researchers at Johns Hopkins went to corner stores in predominantly black neighborhoods and posted signs with calorie information about sugary drinks (sodas, fruit drinks, energy drinks and the like) on refrigerated beverage cases.

Overall, the study found, black teens — a population that is more likely to consume sugary drinks and is at higher risk of obesity than other groups — were 40% less likely to buy soft drinks when they saw the calorie signs. They were even less likely to buy them when the calorie labels put information in context: for instance, by noting that it would take 50 minutes of running to burn off the calories in one sugary drink. Those signs reduced soda consumption by 50%.

A trio of studies published in the New England Journal of Medicine last month suggests that Americans, especially children, could benefit from any effort to reduce soda consumption. The studies showed that limiting kids’ access to sugary drinks — and giving them water or other zero-calorie drinks instead — can help kids lose weight or curb their weight gain. For people who are already genetically predisposed to obesity, the research showed, drinking soda can make their weight problem even worse.

The soda companies’ new initiative, which will also increase the availability of low-calorie and zero-calorie drink options in vending machines, seems to be a step in the right direction. “People tend to overconsume products with sugar and for these companies to be doing something that may decrease consumption of their sugared beverages surprises me,” Kelly D. Brownell, director of the Rudd Center for Food Policy and Obesity at Yale University, told the New York Times. “But it does seem to me to be a positive move.”